Turbines, especially gas turbines, are used in many areas for driving generators or driven machines. In this case, the energy content of a fuel is used to produce a rotational movement of a turbine shaft. For this purpose, the fuel is combusted in a combustion chamber, wherein air, which is compressed by an air compressor, is supplied. The working medium, which is produced in the combustion chamber by means of the combustion of the fuel, is guided in the process at high pressure and at high temperature through a turbine unit, which is connected downstream to the combustion chamber, where it is expanded, performing work.
For producing the rotational movement of the turbine shaft, in this case a number of rotor blades, which are customarily assembled to form blade groups or blade rows, are arranged on said turbine shaft and drive the turbine shaft via an impulse transmission from the working medium. For guiding the working medium in the turbine unit, moreover, stator blade rows, which are connected to the turbine casing, are customarily arranged between adjacent rotor blade rows.
A turbine of this type comprises a large number of component parts or machine components which are suitably positioned in the turbine, subject to predetermined measurements, shapes and/or tolerances. In many cases, it can be desirable in the process to minimize the contact of adjacent machine components or component parts with each other, in order to keep wear of the affected component parts especially low by such means. However, during the operation of the turbine, time and again actually unwanted contact between such component parts can develop, for example as a result of thermal expansions or else as a result of operation-induced vibrations or suchlike which occur, so that certain wear of such component parts occurs. As such machine components, for example a so-called flame tube, a mixing chamber and an inner casing are customarily arranged adjacent to each other in the region of the combustion chamber of the gas turbine. Owing to their design, these machine components have such significant deformations and critical tolerances that during operation of the gas turbine contact between these component parts in some places is unavoidable. As a result of this contact, unwanted and possibly also critical wear, especially during long operating periods, arises, so that the component parts which are referred to have to be inspected at regular intervals and, if necessary, exchanged/repaired.
In order to keep the wear of the affected component parts or machine components especially low in such situations, the machine components can be manufactured in a so-called clad design, wherein the regions which are especially affected by the anticipated wear or the anticipated contacts with adjacent components are covered with a protective lining which is also referred to as cladding. Such a cladding in this case can be formed from a cladding material which in comparison to the base material of the respective components has a greater mechanical hardness, so that by means of such a suitable material selection contact-induced wear which occurs can already be reduced.
On account of the greater hardness of the cladding material which is customary for such application purposes, however, it On account of the greater hardness of the cladding material which is customary for such application purposes, however, it is also more brittle than the respective base material of the base body of the machine component. A further treatment of the base body which is provided with the cladding material, for example by bending or suchlike, is now only possible to a limited extent as a result. Furthermore, during a thermal expansion of the base body, crack formations or other damage can develop in the region which is provided with the cladding material, on account of the different thermal expansion behavior. Particularly for use in thermally comparatively highly stressed regions, such as in the inner region of the combustion chamber of a gas turbine, such clad machine components are only conditionally suitable as a result.